The present invention is directed to a manometer device having dual pressure sensors, and in particular to a manometer device wherein a first pressure sensor is inverted with respect to a second pressure sensor.
Manometers are instruments or devices for measuring the pressure of a fluid such as a gas. In normal applications, manometers that are adapted to sense and measure very low pressures are inherently sensitive to changes in the position of the manometer. This renders low pressure manometers unusable in applicating the position of the manometer may change while attempting to measure and record pressures, such as when hand-held manometers are used. Inaccuracies in pressure measurements that result from a positional change of a manometer are due to the effect of gravity on the diaphragm of the pressure sensor contained in the manometer. A change in the position or orientation of the diaphragm in the pressure sensor of the manometer causes a change in the deflection of the diaphragm due to the force of gravity and the resulting weight of the diaphragm, giving a false indication to the sensor that there has been a change in fluid pressure applied to the diaphragm, although no actual change in pressure occurred when the position of the pressure sensor was changed. For example, when a manometer is initially positioned such that the diaphragm of its sensor is generally parallel to the direction of gravitational pull, and is then rotated ninety degrees such that the diaphragm is perpendicular to the direction of gravitational pull, the pressure sensor will sense a change in the force applied to the diaphragm, but this change in force is due to the weight of the diaphragm and the gravitational force applied to the diaphragm, not a change in the pressure of the fluid that is being measured. The end result is that a manometer having a low pressure sensor previously had to be affixed to a stationary structure in the same position in which it was calibrated for use, otherwise unwanted inaccuracies would result in pressure measurement. The present invention overcomes these problems.
A manometer for measuring fluid pressure. The manometer includes a first pressure sensor including a first housing and a first cover. The first pressure sensor includes a first pressure sensor chip located in said first housing. The first pressure sensor chip includes a first diaphragm, having an interior surface and an exterior surface, that is located in a first plane. The first pressure sensor includes a first fluid chamber that is in fluid communication with the interior surface of the first diaphragm and a second fluid chamber that is in fluid communication with the exterior surface of the first diaphragm. The first pressure sensor includes a first port in fluid communication with the first fluid chamber and a second port in fluid communication with the second fluid chamber. A plurality of electrical contacts are in electrical communication with the first pressure sensor chip. The first port of the first pressure sensor is adapted to be placed in fluid communication with a source of fluid pressure, and the second port of the first pressure sensor is adapted to be placed in fluid communication with a source of fluid pressure. The first pressure sensor is adapted to provide a first electrical output signal representing a fluid pressure measured by the first diaphragm of the first pressure sensor.
The manometer includes a second pressure sensor including a second housing and a second cover. A second pressure sensor chip is located in the second housing. The second pressure sensor chip includes a second diaphragm, having an interior surface and an exterior surface, that is located in a second plane. The second pressure sensor includes a first fluid chamber in fluid communication with the interior surface of the second diaphragm and a second fluid chamber in fluid communication with the exterior surface of the second diaphragm. The second pressure sensor includes a first port in fluid communication with the first fluid chamber of the second pressure sensor and a second port in fluid communication with the second fluid chamber of the second pressure sensor. A plurality of electrical contacts are in electrical communication with the second pressure sensor chip. The first port of the second pressure sensor is adapted to be placed in fluid communication with a source of fluid pressure and the second port of the second pressure sensor is adapted to be placed in fluid communication with a source of fluid pressure. The second pressure sensor is inverted with respect to the first pressure sensor with the second plane being generally parallel to the first plane. The second pressure sensor is adapted to provide a second electrical output signal representing a fluid pressure measured by the second diaphragm. The first and second electrical output signals are combined into a combined electrical output signal wherein false readings of a change of pressure measured by the first pressure sensor, due to movement of the manometer, contained in the first electrical output signal are cancelled by counterpart false readings of a change in pressure measured by the second pressure sensor, also due to movement of the manometer, contained in the second electrical output signal such that the combined electrical output signal provides an accurate indication of the fluid pressure regardless of movement of the manometer.